Patent GB-446808-A (GB)
Title: Improvements in or relating to electric motor control systems
IPC: B60L15/04
Filed: 1935-11-06
Abstract: 446,808. Master control of D.C. motors; actuating controllers. WESTINGHOUSE ELECTRIC & MANUFACTURING CO., East Pittsburg, U.S.A.-(Assignees of Riley, L. G. ; 905, Milton Street, Pittsburg, U.S.A.) Nov. 6, 1935, No. 30725. Convention date, Nov. 13, 1934. [Class 38 (iii)] Field and armature control ; non -regenerative braking.-Motor control apparatus comprises displaceable contact members 31-48, Fig. 1C, arranged around the inside of a sectional busbar 14, 15, 16, and a number of rollers 11, 12, 13 adapted to move the contact members into engagement with the bus-bar to shunt steps of resistances 22, 23. For accelerating purposes the rollers 11, 12 only are used, the roller 13 being held out of engagement with the contact members by a cam 24 and plunger 30 for all positions but those in which rheostatic braking is effected, the resistance 23 is connected in parallel to the two sets of contact members 43-48, and 31-36. The rollers are actuated by a common shaft 18 driven by a pilot motor 19, Fig. 1B, having fields 27, 28 for forward and reverse rotation, and fed from a suitable source of supply such as a battery. The motor 19 also operates cam switches A, D, E, H, K, L, N, M, V, W, Y, T, Fig. ID, for effecting control of the pilot motor and main motor circuits. The control apparatus is described in connection with a master control system for two traction motors 1, 2, Fig. 1A. Upon movement of a master controller MC to its parallel position, a line switch LS is closed by the energization of a circuit including the cam switch A, contactors J, JR, also being energized to complete the series connection of the motors in series with the resistances 22, 23, and additional resistances 5, 6. Contactors R1, R3 are then closed in sequence to cut out the resistances 5, 6. A relay PR then closes to energize the pilot motor 19 which operates the accelerating controller 10 to cut out resistances 22, 23 in steps, the pilot motor being under the control of an inertia device 51 which controls relays AR1, AR2, which shunt resistances 54, 55, connected across the pilot motor armature, the arrangement providing for constant acceleration. The operation of the pilot motor is further controlled by a main current relay LA which shunts, in addition to the resistances 54, 55, further resistance 56. When the roller 11 has been operated to the contact finger 36, the cam switch D is opened to de-energize the contactor JR and give the full series position. Since the controller MC is in its parallel position, the operation of the pilot motor continues, the cam switch V being closed to energize contactors P, G, the closing of the contactor G causing the contactor J to open. The motor circuits are thus changed to parallel connection, the motor circuit being maintained during the transition by the closure of contact members 35, 36, by a push rod 25 operated by a cam 26. The resistances 22, 23 are then removed from the parallel motor circuits. When the contact member 41 is closed the cam switch T closes to shunt resistance 54, 55, 56 to slow down the pilot motor, and, when the contact member 42 is operated, the cam switch M opens to cause the pilot motor to stop. The cam switch E is then closed and contactors 81, 84 close in sequence to shunt the series fields of the motors by resistances 147, 148. This gives the full parallel position. By returning the controller MC to a position " switching," resistances 5, 6 may be reinserted in the motor circuit and the switching sequence held up at any stage. When the controller MC is returned to the off position the line switch LS opens, and the pilot motor is energized by the closure of a circuit including the cam switch K, and operates to an initial braking position. If power is to be re-applied the controller MC is moved to one of its running positions, the relay PR is energized by the closure of a circuit including the cam switch N, and the pilot motor operates the acceleration controller to its initial position in which the cam switch A is closed to allow the line switch LS to close. The acceleration then progresses as before. If dynamic braking is to be applied the controller MC is moved to the braking position whereupon contactors P, G, B close to connect the motors with the armature of one supplying the field of the other, resistances 5, 7, 8, 9, 22 and 178 being connected across one motor armature and resistances 178, 7, 8, 9, 23 and 6 across the other, the common connection including the coils of current relays AL, LB. In the initial braking position of the controller 10 the roller 13 is released and depresses the contact finger 37, the rollers 11, 12 operating during braking on the same resistance 23. The current relay AL prevents shunting of the motor field windings during braking until a predetermined current is reached, which value is comparatively low to avoid excessive braking. Upon completion of the braking circuits the switches B1, B3, B5 close in sequence to shunt the resistances 7, 8, 9, the sequential action being under the control of the braking limit relay LB. While relays B1, B3, B5 are closing the relay AL permits switches S1, S4 to close in sequence to shunt the motor fields. When relay B5 has closed, relays R1, R3 close in sequence to shunt the resistances 5, 6, this switching sequence also being under the control of the limit relay LB. When R3 closes the relay PR is energized and the controller 10 is operated under the control of the relay LB. When the braking movement of the controller 10 is completed the cam switch L opens to stop the pilot motor 19. Braking resistance 178 is left in circuit and the air brakes are applied to bring the vehicle to rest. The braking sequence may be stopped at any stage by returning the controller MC to the position " Hold." When the controller MC is moved to the "off" position, the controller 10 remains in the final braking position until the controller MC is moved to an accelerating position, whereupon the relay PR is energized over a circuit including the cam switch N and the pilot motor operates to the initial position. If, during acceleration, the controller MC is moved to the off position before the roller 11 has reached the contact member 36, i.e. during series operation, the controller 10 moves back to the initial position, the pilot motor reverse circuit being completed over the cam switch H. If the controller MC is moved to a braking position while the motors are in series, a relay AR3 is energized to cause the completion of the forward circuit of the pilot motor over cam switch K so that the controller 10 is moved on into the braking position. Specification 431,224 is referred to.